When programming, one has to recognize that there is no "need" for any station. Usage is created by convenience and opportunity. So, if one broadcast group wants to bring down a market leader by a bit, they counter program to slice away shares from the competitor. The result is that the competitive group has fewer shares and the creator of the strategy enhances their own relative rank positions.
When I owned 9 stations in a market, I knew that one of them would always be in play to counter a move or format variation of a competitor. It did not matter if each station individually made money as I had taken the example from business textbooks of supermarkets where some products were loss leaders to bring traffic that would buy profitable things.
Listeners will have an array of stations they use; the PPM shows us that the average person uses 6 stations in a 7 day period. And even in the past we knew that even the early push button car radios could be set for five or six stations. Anything that fragments a competitor will bring benefits to us.
Programming decisions are based as much or more on advertiser needs as on listener tastes.